Murder is in the air this week. At the Almeida Theatre The Novice, adapted by Richard Eyre from Jean-Paul Sartre, debates the ethics of assassination. And in David Gieselmann's Mr Kolpert at the Royal Court an affluent young couple "entertain" their guests with the idea that there is a corpse in the living-room trunk. Both plays are European; both use the thriller format; both feature bourgeois protagonists. But what is fascinating is that Gieselmann's sardonic comedy seems much more lethally political than Sartre's heavyweight melodrama.
I am wary of calling Sartre's play dated, simply because it was written in 1948. As John Lahr once wrote, "all drama is dated, the product of a particular moment". And nothing is dafter than to attack plays simply because they don't conform to our own values and circumstances. We don't believe in divine monarchy, but Richard II is still a potent analysis of the fallibility of power. Venereal disease may now be curable, but it doesn't stop Ibsen's Ghosts being a powerful attack on inherited guilt. All good plays exist in a dual time-frame: they embody their own period while expressing eternal truths.
Eyre's tactical error in The Novice is to abstract Sartre's play from its times. He gives us bags of 40s film noirish atmosphere. But, in a play that is all about a bourgeois rebel assigned to kill a compromising communist, he deletes all reference to the Soviet Union. This strikes me as bizarre, since the whole play is about the tentacles of Moscow's power.
In Eyre's version the hero, having committed the murder, is baldly told by his minder, "we've changed our policy". In Sartre's original it is spelt out clearly: contact with the USSR was interrupted by war and the local party chose to pursue its own line, whereas in the postwar world it has to kow-tow to Moscow orthodoxy. Eyre excises the specifics, leaving Sartre's play floating in political limbo.
But Sartre's form also looks suspect. There was a time when I found his mix of melodrama and politics exciting. What strikes me now is that he tries to spice up his ideas with desultory sex. Sartre gives his hero a glam wife who oscillates between coy flirt, frigid ice-maiden and romantic victim: she is simply used as top-dressing - or sometimes undressing - for the political debates. My hunch is that, if you are going to revive the play today, you have two choices: either acknowledge its strengths and weaknesses and do it as all-out dialectical debate, or, as Frank Castorf does in his jazzy version at the Berlin Volksbuhne, treat it as rampant expressionism. What you can't do is strip it of all context.
Ironically, Gieselmann's Mr Kolpert, although seemingly apolitical, has much more social content. Like Sartre's play it is about the morality of murder. The well-heeled Ralf and Sarah entertain married guests and tease them with the idea that there may be a dead body in the trunk. But the key moment comes when Sarah explains, in David Tushingham's translation, the affluent vacancy of their lives: "Ralf and I kept seeing people our age dancing, trying hard to pretend they'd just left school a few weeks ago and that emotions and all that stuff are just a bit of a laugh. But beneath all that they were really human beings. Then we realised we weren't aware of emotions any more either. All we wanted to do was feel something again."
If that strikes a chord it is with the world of Sarah Kane and with Mark Ravenhill's Shopping and Fucking and Some Explicit Polaroids. What all these German and British writers seem to have spotted is that the real danger in modern society is of a sawn-off sensibility and a detachment from feeling. A shrewd academic pointed out to me this week that there is nothing new in this: Wordsworth was making the same complaint in his Preface to the Lyrical Ballads. But what modern dramatists have detected is that we now seek dangerous substitutes - chemical substances or, in extreme cases, killing - to compensate for our emotional void.
That is why I would call Mr Kolpert a deeply political play. It suggests valueless affluence leads to desperation. In Sartre's world people kill for a cause; in Gieselmann's they murder, or toy with it, out of ennui. Sartre warns us against the dangers of excess idealism: Gieselmann against a total lack of it. Fifty years separate the two plays which together paint a graphic picture of modern Europe. If I find Gieselmann's infinitely more terrifying it is because it suggests we now live in a world where violence is the product less of political passion than of bourgeois boredom. How on earth do we counter that?
• The Novice is at the Almeida Theatre, London N1 (020 7359 4404) till June 17; Mr Kolpert is at the Royal Court, London SW6 (020 7565 5000) till May 20.
